vite/references/rolldown-migration.md

---

name: vite-rolldown description: Vite 8 Rolldown bundler and Oxc transformer migration

---

Rolldown Migration (Vite 8)

Vite 8 replaces esbuild + Rollup with Rolldown (Rust bundler) and Oxc (Rust transformer/minifier).

What Changed

Before (Vite 7)	After (Vite 8)
esbuild (dev/JS transform)	Oxc Transformer
esbuild (dep pre-bundling)	Rolldown
esbuild (CSS minify)	Lightning CSS (default)
Rollup (production build)	Rolldown
build.rollupOptions	build.rolldownOptions
worker.rollupOptions	worker.rolldownOptions
optimizeDeps.esbuildOptions	optimizeDeps.rolldownOptions
esbuild option	oxc option

Backward Compatibility (Auto-Conversion)

Old options are deprecated but still work — Vite converts them internally:

• esbuild → oxc
• build.rollupOptions → build.rolldownOptions (alias)
• optimizeDeps.esbuildOptions → optimizeDeps.rolldownOptions

Migrate to the new names; the compat shims will be removed in a future major. Read the converted values from the configResolved hook (config.oxc, config.optimizeDeps.rolldownOptions).

Default Browser Target Change

build.target / 'baseline-widely-available' moved to newer versions (Baseline Widely Available as of 2026-01-01):

• Chrome 107 → 111, Edge 107 → 111, Firefox 104 → 114, Safari 16.0 → 16.4
• Resolves to ['chrome111', 'edge111', 'firefox114', 'safari16.4', 'ios16.4']
• Default --minify is now oxc (was esbuild)

Config Migration

rollupOptions → rolldownOptions

export default defineConfig({
  build: {
    rolldownOptions: {  // was rollupOptions
      external: ['vue'],
      output: { globals: { vue: 'Vue' } },
    },
  },
})

Prefer the top-level input option over build.rolldownOptions.input — it applies in dev too.

esbuild → oxc

export default defineConfig({
  oxc: {  // was esbuild
    jsx: {
      runtime: 'classic',
      pragma: 'h',
      pragmaFrag: 'Fragment',
    },
  },
})

esbuild.jsxFactory→oxc.jsx.pragma, jsxFragment→oxc.jsx.pragmaFrag, jsx: 'transform'→oxc.jsx: { runtime: 'classic' }, jsx: 'automatic'→{ runtime: 'automatic' }. esbuild.banner/footer have no equivalent — use a custom plugin transform hook.

JSX Configuration

export default defineConfig({
  oxc: {
    jsx: {
      runtime: 'automatic',  // or 'classic'
      importSource: 'react', // for automatic runtime
    },
    jsxInject: `import React from 'react'`,  // auto-inject
  },
})

Custom Transform Targets

export default defineConfig({
  oxc: {
    include: ['**/*.ts', '**/*.tsx'],
    exclude: ['node_modules/**'],
  },
})

Notable Breaking Changes

• build() throws BundleError (JS API): typed Error & { errors?: RolldownError[] }. Access individual errors via e.errors.
• build.rollupOptions.output.manualChunks: object form removed, function form deprecated. Use Rolldown's codeSplitting.
• build.rollupOptions.watch.chokidar removed → build.rolldownOptions.watch.watcher.
• resolve.alias[].customResolver deprecated → use a custom plugin with a resolveId hook and enforce: 'pre'.
• build.commonjsOptions is now a no-op.
• require calls for externalized modules are preserved as require. To convert to import, use the re-exported esmExternalRequirePlugin.
• import.meta.hot.accept(url) no longer accepts a URL — pass an id.
• Unsupported by Rolldown: output format 'system'/'amd', shouldTransformCachedModule, resolveImportMeta, renderDynamicImport, resolveFileUrl hooks.
• Native decorator lowering is not yet supported by Oxc — use @rolldown/plugin-babel or @rollup/plugin-swc as a workaround.

Detecting Rolldown-powered Vite

buildStart() {
  // only defined on Vite 8+ (Rolldown)
  if (this.meta.rolldownVersion) { /* ... */ }
}

Also exported from vite: version, rolldownVersion (esbuildVersion/rollupVersion kept only for back-compat).

Plugin Compatibility

Most Vite plugins work unchanged — Rolldown supports Rollup's plugin API. Rolldown runs all parallel Rollup hooks sequentially. If a plugin only works during build:

{
  ...rollupPlugin(),
  enforce: 'post',
  apply: 'build',
}

New Capabilities

• Full bundle mode (experimental, vite --experimentalBundle)
• Chunk import map optimization (build.chunkImportMap)
• More flexible chunk splitting / Module Federation support

Gradual Migration

rolldown-vite is Vite 7 running on Rolldown without other Vite 8 changes — an intermediate step:

# Step 1: swap vite for rolldown-vite on Vite 7 (npm alias in package.json)
#   "vite": "npm:rolldown-vite@^7"
# Step 2: undo the alias and upgrade to Vite 8
pnpm add -D vite@8

If migrating from rolldown-vite, only the "NRV"-badged sections of the official migration guide apply.

Overriding Vite in Frameworks

When a framework depends on older Vite:

{
  "pnpm": {
    "overrides": {
      "vite": "8.0.0"
    }
  }
}